Problem: Solve for $x$ : $24 = -18 + x$
Explanation: Add $18$ to both sides: $ \begin{eqnarray} \\ \hphantom{24 {+ 18}} &\hphantom{=}& \hphantom{x} \\ 24 &=& -18 + x \\ \\ {+18} && {+18} \\ \end{eqnarray} $ $ \begin{eqnarray} \\ 24 {+ 18} &=& x \\ \end{eqnarray} $ Simplify. $ x = 42$